揭开火星陨石之谜

20世纪80年代科学家已掌握了可靠的证据证明降落在地球上的一些陨石来自火星:通过对被幽禁在这些岩石内的气体进行分析发现,它们与1976年海盗号飞船探测火星时其着陆器对火星大气的测量结果一致.这些岩石一定是当小行星撞击此红色行星时从火星表面炸出,并在太阳系内游荡了几百万年后坠毁在地球上的.但美国亚利桑那大学的     

无环流不断电切换谐波起动感应电动机的研究（I）—无环流不断电切换定子绕组设计

谐波起动电机是一种新型的电动机。研究了该类电动机的设计方法，介绍了无环流、不断电切换的定子绕组方案及计。     

让星光不再颤动：展现一个更清晰的宇宙

晴朗的夏夜,黑天鹅绒般的天空闪烁着无数的光点。闪烁的星光曾激起一代又一代文学家和诗人丰富的想像力和创作灵感,但是对于那些致力于观察星空探索宇宙的天文学家来说,星星眨眼却是他们观察宇宙的极大阻碍,闪动的星光使得他们不能更清楚地观察遍布在浩瀚宇宙中的星系、恒星和行星。牛     

Role of Ferrel cell in daily variability of Northern Hemisphere Annular Mode

The Northern Hemisphere Annular Mode(NAM) represents the zonally symmetric planetary-scale atmospheric mass fluctuations between middle and high latitudes, whose variations have shown a large impact on other components of the climate system. Previous studies have indicated that the NAM is correlated with the Ferrel cell in their monthly or longer timescale variability.However, there have been few studies investigating their connections at daily timescale, though daily variability of NAM has been suggested to be an important component and has significant implication for weather forecast. The results from this study demonstrate that variability of the Ferrel cell leads that of the NAM by about 1–2 days. This statistically identified temporal phase difference between NAM and Ferrel cell variability can be elucidated by meridional mass redistribution. Intensified(weakened)Ferrel cell causes anomalously smaller(larger) poleward mass transport from the middle to the high latitudes,resulting in an increase(a decrease) in mass in the middle latitudes and a decrease(an increase) in the high latitudes.As a consequence, anomalously higher(lower) poleward pressure gradient forms and the NAM subsequently shifts to a positive(negative) phase at a time lag of 1–2 days. The findings here would augment the existing knowledge for better understanding the connection between the Ferrel Cell and the NAM, and may provide skillful information for improving NAM as well as daily scale weather prediction.     

First scanning Fabry-Perot interferometer developed in China

A scanning Fabry-Perot interferometer （SFPI） was first developed and deployed at the Langfang near Space Environment Field Scientific Observation Station （39.38°N, 116.65°E） of the National Space Science Center, CAS. The instrument is designed to measure the mesospheric and ther- mospheric wind velocities using the atomic oxygen 557.7-nm and 630.0-nm emissions. Data from February 28 to March 3 and February 28 to March 15 in 2011 were chosen for case study and mean value study, respectively. The errors of the meridional and zonal winds are 6.5 and 7.5 m/s at 557.7-nm and at 630.0-nm, they are 7.1 and 6.6 m/s, respectively. During the whole experiment, the instrument has performed in good condition and provided high-quality data. The mean neutral wind data were consistent with that predicted by HWM07. Good agreement has been found in between the SFPI and a neighbor Meridian Project Fabry-Perot interferometer （MP FPI）, with a corresponding coefficient （re） larger than 80 %. In general, the scanning FPI meets the design goal, and it is a useful ground-based instrument for measuring mesospheric and thermospheric winds at middle latitudes and is able to provide high-quality data for future scientific studies.     

侧向散射激光雷达反演气溶胶后向散射系数误差分析

气溶胶的光学特性是大气探测的一个重要部分,侧向散射激光雷达很适合于探测近地面大气气溶胶光学特性。在侧向散射激光雷达的反演公式中,气溶胶后向散射系数对各直接测量量偏导数的解析表达式是求不出的,传统的误差传递公式难以发挥作用。而直接误差传递的方法,适应于这种情况。用直接误差传递方法估算参考点气溶胶后向散射系数、大气后向散射系数、气溶胶消光后向散射系数比、测量信号、大气分子和气溶胶比相函数分别独立变化时引起后向散射系数误差的大小及总误差的大小。     

西沙严酷海洋大气环境下AZ31镁合金的长周期腐蚀行为

通过现场暴露实验,研究了AZ31镁合金在西沙海洋大气环境下暴露4 a的长周期腐蚀行为.利用扫描电镜观察表面、截面的腐蚀产物以及去除腐蚀产物后的腐蚀形貌,并用能谱分析及X射线衍射仪对腐蚀产物的元素含量及相组成进行分析.研究结果表明,AZ31镁合金在西沙海洋大气环境下发生了较为严重的腐蚀,4 a内的平均腐蚀速度为11.95μm·a-1.Cl-和CO2在镁合金的腐蚀过程中起着至关重要的作用.吸附液膜中的Cl-主要破坏镁合金的保护膜,使镁合金发生阳极溶解;而CO2则会中和阴极反应产生的碱性离子并与Mg(OH)2发生反应生成含不同结晶水的Mg5(CO3)4(OH)2·xH2O表层腐蚀产物.由于表层腐蚀产物阻挡了CO2和Cl-向镁合金表面的传输,靠近基体处的腐蚀产物主要为Mg(OH)2.     

冬季Hadley环流活动与大气臭氧变化的关系研究

 利用1957年9月到2002年8月,共540个月的ECMWF的经向风和臭氧质量混合比资料,分析研究了冬季Hadley环流强弱特征的变化对臭氧变化的影响.分析指出在冬季伴随Hadley环流的增强,其中心南移,高度升高,臭氧在对流层增加,平流层减少,臭氧总量呈现出减少的趋势.Hadley环流的增强,中心南移,高度升高以及臭氧在对流层的增加对全球变暖是正反馈,而平流层臭氧减少,臭氧总量减少对全球变暖是负反馈.因此Hadley环流的强弱对臭氧的影响明显.     

伶仃洋西槽洪季水沙纵向输移机制研究

根据2003年实测数据,运用物质纵向输移模式计算了丰水大潮期伶仃洋西槽的水量和泥沙纵向输移量,研究了伶仃洋西槽洪季水沙纵向输移机制及水量输移特征,并针对泥沙输移特征,用底层流速和含沙量的相位变化以及表底层盐度的变化对悬沙输移机制进行了分析.结果表明:伶仃洋西槽垂向环流发育,泥沙输移特征明显;径流、潮流变形以及盐淡水异重流是形成西槽水量输移的主要原因;潮流不对称性和底层泥沙再悬浮对潮汐捕集输沙的贡献明显,盐淡水混合和纵向水体梯度对垂向净环流输沙的贡献明显.